'The court was considering not the more recent uses of kettling but the policing of a May Day demonstration in 2001.' Photograph: Peter Jordan/PA

The European court of human rights has delivered its eagerly awaited judgment on the lawfulness of the police tactic of "kettling" or containment. The use of this tactic at the G20 protests in 2009 – when Ian Tomlinson was unlawfully killed while trying to get through a police cordon – and at student and anti-capitalist protests, has led to fears that it is being deployed as a routine crowd control measure.

Cuts to public services and the NHS, increases in student fees and attacks on welfare benefits all mean that there is more and more reason to take to the streets against government policies. But the prospect of being kettled, detained against your will in a crowd for many hours, is a serious deterrent and has an obvious chilling effect on the right to demonstrate. Moreover the use of kettling is thought by many to increase the risk of public disorder by making people feel justifiably angry.

It was hoped that the European court would shed some reason and light on this debate and rise above self-interested government arguments. Sadly that has not happened. This may be because the court was considering not the more recent uses of the tactic but the policing of a May Day demonstration in 2001.

The case was brought by a client of my firm, Lois Austin, and three others. Austin was at the demonstration as a protester. She was detained for seven hours without access to food or water or toilet facilities, and was unable to collect her baby daughter from a creche as planned. The three other applicants – George Black, Bronwyn Lowenthal and Peter O'Shea (who were separately represented) – were not part of the demonstration but just happened to be in Oxford Circus at the time. Two of them were working in the area and on their lunchbreaks, and one was shopping there. They were detained for similar periods of time in the same conditions.

They all complained that their detention was a deprivation of liberty which could not be justified under Article 5.1 of the European convention. Before the case came to the European court it had gone through the entire English court system, as is the requirement, with the House of Lords finding in January 2009 that there was no deprivation of liberty.

The majority of the judges in the European court have essentially upheld the Lords judgment and relied on the same rather vague statements made by their lordships. These refer to what the European judges call situations that "commonly occur in modern society where the public may be called on to endure restriction on freedom of movement or liberty in the interests of the common good". Examples given include such events as police stopping cars on a motorway. The bracketing of such an example with restrictions on protesters ignores the tendency of governments and police to want to curb and stifle protest, and is not in any event equivalent to the experience of being corralled for many hours. The assurance in the ECHR judgment that such restrictions on movement are acceptable "so long as they are rendered unavoidable as a result of circumstances beyond the control of the authorities and are necessary to avert a real risk of serious injury or damage and are kept to the minimum required for that purpose" does not convince that it places any real requirements on the police imprisoning people in the street.

The judgment of the majority is skewered by an impressive dissenting judgment of three judges (from Belgium, Luxembourg and Poland) led by Françoise Tulkens. They point out that the special treatment of deprivation of liberty arising from public order considerations is a dangerous precedent, singling out the words quoted above as sending "a bad message to police authorities". They also point out that, in the case when the European court ruled against the UK government on the indefinite detention of foreign nationals, the court did not accept Britain's attempt at special pleading for national security cases and similarly should not do so here for public order reasons. They say that there are better methods of controlling a crowd than an indiscriminate cordon applied even to non-demonstrators.

"The police could have been expected to apply less intrusive means. As it was, it seems that all people who happened to be at Oxford Circus at around 2pm were treated like objects and were forced to remain there as long as the police had not solved other problems around the city."

Cases relating to more kettling at more recent protests have been put on hold pending this ruling and one can only hope that when the supreme court considers whether the containment of the climate change camp sit-in at the G20 protest is lawful, it will impose a more stringent test than is to be found in this disappointing decision.